Researchers make key discovery toward engineering breast tissue

Credit: Courtesy of Carnegie Mellon University Credit: Courtesy of Carnegie Mellon University

A Carnegie Mellon research team from the bioengineering and mechanical engineering departments has published a paper in the journal Biotechnology and Bioengineering that describes their research on a way to control localization of tissues, which allows researchers to shape those tissues as needed.

This ability has given researchers the tools they need to mimic the way mammalian breast tissues align to form hollow tubes for the transportation of milk.

“In mammalian bodies, breast cells align to form hollow tubes, where milk is transported,” said Jimmy Hsia, a professor in the departments of Biomedical Engineering and Mechanical Engineering at Carnegie Mellon and corresponding author of the study, in a university press release. “To date, no one has been able to generate breast tissue with these hollow tubes. Our study is the first step toward realizing such functionalities in reconstructed breast tissues.”

According to the article, this form of fine-control over tissue construction has never been possible before, which makes this creation of functional breast tissue a very important step in tissue engineering.

“We grew breast cells in a 3-D environment, and they aligned themselves along certain geometrical features of the substrate,” Hsia said in the press release.

It was only recently determined that mechanical signaling along with biochemical signaling assists with changes in the body.

Though research has been done on the effect of mechanical signaling and its responses, more sophisticated tools were required to form intricately shaped tissues. Studying one such mechanical factor, like the relationship between the stiffness of the substrate and the response of the cells in vitro, has previously been done, but only in two dimensional environments.

The drawback of two dimensional environments is that it resembles “experimental conditions” like a glass or a petri dish, but not actual three dimensional tissues.

The study conducted above mentioned experiment in a three dimensional environment and concluded that the stiffness gradient of the tissue scaffold to which the cells bind and take their shape, as well as the localized stiffness, played a key role in how cells moved, as opposed to the stiffness of the bulk of the tissue scaffold.

This particular fact allowed the team greater control over specific features of the tissue’s construction, including the spacing between tube-like structures.

The setup used in the study was a three dimensional matrix with continuously changing height, an extracellular environment with varying stiffness gradient, while other factors such as fiber density and protein concentration were kept constant.

This experiment was conducted on four different cell types and various substrates.

However, more research needs to be done with respect to other factors such as the relationship between cell velocity and stiffness gradient, the adhesion forces exerted by the cells, and the displacement of cells.

This study can potentially help mothers regain their nursing ability after having reconstructive surgery, which make breasts functional again, along with reinstating them to their original form, a viable option. This method has the potential to be applicable in a variety of fields including tissue engineering, regenerative medicine, cellular machines, and mechano-biology.

“We know many people receive mastectomies and many of them do reconstruction, but none of these reconstructed breasts are functional,” Hsia said in the press release. “We believe we’re on our way toward achieving that.”